why TypeScript

types are associated with run-time valaues

dynamically typed language static type, less error-prone

type checking is not done in runtime but before compiling or during development

ts file is compiled down to js extra features shape of an object, better maintenance and autocomplete

为JavaScript添加了静态类型

通过TypeScript compiler或Babel转译为JavaScript

静态类型在开发阶段就可以减少bug从而在一定程度上提升开发效率

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